In the context of AMR, most existing techniques use either:
i) a proprietary network installed wholly for the purpose of reading meters, such as a bespoke radio network, or
ii) a pre-existing network wholly installed to support commodity delivery. An example of the latter type of network is the power line carrier (PLC) network, which uses existing electricity power supply lines to confer them the additional role of transporting electricity meter (or other meter) readings.
Other known techniques use a third party network, typically the public switched telephone network (PSTN) lines, to read meters at preselected times and at preselected frequencies (e.g. monthly). In this case, the meters can be polled from a master system, i.e. the meters are accessed and ordered to send their readings, or the meters can contact the master station at a set time and deliver their meter readings.
Approach i) above suffers from the problem that a suitable network must be maintained solely for the purposes of reading a meter, and therefore the cost of maintaining and installing the network is normally not recovered from the savings made in automatic meter reading, or at least the payback is too long to make the investment viable.
Approach ii) above is a high cost solution, since the network provider typically does not extract sufficient revenue from the meter reading activity to offer low enough tariffs for making automated meter reading cost effective. Because the readings take place at a preselected time, they do not take into account the current level of network usage at that time. The networks in use are not optimised for meter reading, and therefore do not offer a cost effective solution for that application.
In an attempt to minimise AMR data traffic over a radio network, it has been proposed in patent document U.S. Pat. No. 6,133,850 to provide utility meters with a function of internally storing pricing information, allowing the meters to calculate for themselves billing cost locally on the basis of the downloaded pricing information. The totalised billing determined by the meter is sent in place of the utility consumption data, thereby allowing the frequency of data exchanges to be reduced.
Patent document US 2003/0048199 describes a modular radio network for AMR applications, in which base stations are interconnected by an IP network, and the collected information is grouped at a central station for later access.
Patent document EP-A-0 77 8688 more particularly addresses the problem of software and firmware compatibility among meter manufacturers and utilities operators, whereby existing commercial software packages can be used without reconfiguring or relinking the system.